Dear visitor, welcome to SPRINKLER TALK FORUM - You Got Questions, We've Got Answers. If this is your first visit here, please read the Help. It explains how this page works. You must be registered before you can use all the page's features. Please use the registration form, to register here or read more information about the registration process. If you are already registered, please login here.

Low pressure on 1 zone

I have seen a large amount written on this subject, but I cannot find one that fits my situation. I have a 9 zone system with Hunter PGV-ASV valves. I installed all 9 valves new on my system since a few of the old valves had issues. My zone 5 never really acted right even after changing the valve. I ended up installing all new PVC to the sprinkler heads hoping this would fix the low pressure problem. It basically had no pressure before I re-plumbed due to some leaks in the pipes. I am getting more pressure now, but not the correct amount.

I have already changed the valve out for a completely new valve. I have switched the top end from one of the working valves to the one that gives the low pressure. I have also tried solenoids from the other zones. If i just turn on zone 5 (low pressure zone) either manually or electrically it gives what I would consider to be about 60% pressure. After banging my head against the wall literally and figuratively I just started doing random things. The thing that has made zone 5 go to 100% is really weird. I turn on zone 5 and it give the standards 60% pressure. I open another zones bleed valve or main valve for a split second and then close it and then voila 100% pressure on zone 5.

This is obviously not a practical way for me to get the zone to water my newly placed sod consistently. Any help is appreciated...this is driving me insane. Thank you.

Just 3 rainbird sprinklers on the zone. I have other zones that have 3 and work fine with no "workaround". Like I said, it is really weird, they do get full pressure but only after popping another zone's valve or bleed open for about 1 second and then close it. Immediately after doing that the pressure on the low pressure zone increases to where it should be. No leaking from the sprinkler heads.

I don't think it is a nozzle problem since I am able to get full pressure with the workaround.

Try using an Irritrol 2713APR antisyphon valve, if you want a "do this and job done" solution, sight unseen.

But first, try some advanced diagnostics. You need a pressure gauge connected somewhere upstream of your zone valves. Open a zone you know works properly. You can do this for all the zones, and log the pressure measurements.

When you get to a zone where the heads aren't popping up, the pressure gauge reading will help you know if the zone valve is the problem. Broken pipe(s) will result in a low pressure reading. A faulty valve not opening fully will result in a reading that is higher than expected.

So you are saying that the valve you listed is just a superior valve? I would be willing to pay $100 for a guaranteed no headache fix. I will try the pressure test with a gauge I guess. It is just a really weird problem. I do get full pressure on the zone, but only after opening the normal valve or bleed valve of another zone for a second and closing it. I know I have said this already, but the zone is capable of getting full pressure this way.

the Irritrol valve is descended from a company named Richdel that was a pioneer in plastic valves, that was an acquisition of a company later bougt by Toro - Richdel valves rarely if ever gave trouble right out of the box, which is a track record other leading brands do not enjoy - if you don't have the gauge for testing the system, your money might as well go to the Irritrol valve

Well, I replaced the valve. Same result. I have to pop a valve or bleed valve on another zone for a second and close it while the low pressure zone is on. This is the only thing that makes the low pressure zone have full pressure.

In my mind, I have no other options. I re-plumbed the entire zone and have tried 3 different valves. This is just crazy to me.

I guess I will just go insane and the grass will not get watered unless I do the workaround whenever I want to water.

When you have low pressure can you go out to the heads and pull them up to seal the heads giving them full pressure?
Also, "RainBird" is a brand, not a type of sprinkler head.
I still think the heads might be the problem. They aren't sealing so they can't pop up, then when the second zone shuts off it sends a little water hammer down the line popping them up the rest of the way and they seal.
You have a brand new valve, the problem must be down the line somewhere.